The interrupting capacity is what decides whether it clears a fault without upstream damage: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 690 V — so at common 400 V class distribution voltages it handles high available fault current without cascading to the main breaker. The thermal-magnetic release is a TM240, meaning the thermal element is fixed at 125 A and the magnetic pickup is set at 240 A (typical for motor or feeder protection where short-circuit instant trip needs to ride through inrush).
The 125 A rating holds flat from 40 °C to 50 °C, then derates: 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C.
The 76.2 mm width (3 inches) is the standard 3-pole MCCB footprint for a 125 A frame — it drops into the same panel cutout as other SENTRON 3VA1 breakers of the same frame size. No rewiring or bus-bar repositioning is needed if replacing a 3VA1112-5EF32-0CA0 or similar 3-pole 125 A variant; the mounting hole pattern and terminal spacing are identical across the frame.